Blurry image covering tools in Pixelmator Pro

The issue that you describe (and show) appears to be a 'blank' tooltip (less likely) or tool selection box (more likely). Tooltips can be disabled in Pixelmator menu > Settings > General tab.

General settings in Pixelmator Pro on Mac - Apple Support

If that doesn't help, try these ways to clear it:

The "Invisible X" Trick

According to some posts, users have successfully dismissed these phantom boxes by carefully moving their cursor over the top-left corner of the blank popup and clicking blindly around the area where the standard red "Close" (X) button would normally reside.

Completely Quit and Relaunch Pixelmator

Press Cmd + Q while Pixelmator Pro is active to completely shut down the application and clear out its dynamic processes. If the popup disappears immediately when the app closes, you can narrow down the trigger to an unrendered extension or tool tip.

Clear Pixelmator's App Cache

If the issue happens specifically when you interact with certain panels or menus inside Pixelmator Pro, reset the app's cached window layouts:

• Quit Pixelmator Pro.
• Open Finder, press Cmd + Shift + G, and paste the following then press return:

~/Library/Containers/

• Locate the Pixelmator Pro folder (or com.pixelmator.pixelmatorpro) and drag it to the Trash.
• Reopen the app to regenerate clean interface files.

The above procedure is from Apple's troubleshooting instructions (#12), there are other steps there to try as well:

If Pixelmator Pro isn't working - Apple Support

Thanks I will look into these things.